Vapor-dispensing devices such as air-fresheners and the like typically include a reservoir and a transport system from which a fragrance or other volatizable material can be evaporated into the surrounding environment. As an individual's subjective response to an airborne fragrance will vary according to, inter alia, the nature of the scent, the olfactory sensitivity of the individual, and the extent to which other unwanted odors exist in the environment, it is not unusual for such vapor-dispensing devices to include some form of apparent control over the intensity of fragrance or other vapor released into the environment. These control-systems typically take the form of adjustable venting configurations and or components which selectively adjust the proximity of a heating element to the wick and/or reservoir of volatizable material.
Such methods of providing a controlled amount of vapor may be unsatisfactory in a number of respects. For example, while known vapor-dispensing devices allow the user to move a slider, knob, or other such control to modulate fragrance output, the resulting effect on actual evaporation rate may be negligible, resulting in a device which effectively delivers vapor at a single evaporation rate.
Even in cases where the evaporation rate of a prior art vapor-dispensing device offers a range of evaporation rates, the actual corresponding range of sensory fragrance intensity values (i.e., the actual subjective response to particular vapor density and/or evaporation rates) may often be indiscernible.
Furthermore, such prior art devices typically function at only the extremes of their operating range; i.e.—while the device might include a slider, knob, or other such component which can be moved over a continuous range (or between a number of discrete settings), the device itself will generally not operate at intermediary values falling within the continuous range.
Thus, there exists a need for a vapor-dispensing device which is controllable and which operates between a meaningful range of sensory fragrance intensities.